Textured vinyl pull cap

ABSTRACT

A vinyl pull cap having a texturized grip surface is provided comprising a tubular vinyl dip-molded tubular member having a closed end and an open end, with the tubular member having an outer second texturized dip-molded vinyl surface layer covering at least a portion of said tubular member comprising particles of a size and in an amount sufficient to provide a texturized outer vinyl surface.

BACKGROUND OF THE PRESENT INVENTION

The present invention is directed to a pull cap having a textured gripsurface.

Pull caps have been used commercially for many years. These caps havemany uses, such as sealing the ends of tubes, pipes, or other articlesof manufacture that may have an open end which needs to be temporarilysealed during manufacturing, storage, transportation, etc.

By way of example, U.S. Pat. Nos. 3,574,312 and 6,520,212 discloseseveral embodiments of protective plastic end caps for use in protectingthe open end of a tube, etc. As shown by U.S. Pat. No. 3,574,312, suchend caps can easily be made by means of a vinyl dip molding process.

Current commercially-produced vinyl end caps have an inherently slipperysurface due to the lubricity properties of the vinyl material, theinherently smooth surface of the vinyl material, as well as the presenceof plasticizers (oily softeners) that tend to leach from the surface ofthe vinyl material over time.

As protective end caps generally are not provided withergonomically-friendly configurations which might serve to assist ingripping of the end cap, it is sometimes difficult to remove the end capfrom engagement with an article to be protected if the respective fitbetween the end cap and the article is snug or tight. As the degree ofprotection is enhanced by a snug or tight fit, this problem tends tooccur with some frequency. Also, over time the surface of the end captends to adhere to the surface to be protected more aggressively, thusfurther hindering removal of the end cap from engagement.

OBJECTS AND SUMMARY OF INVENTION

It is thus an object of the present invention to provide a protectiveend cap which has the capability to both effectively serve a sealing orcapping function, as well as to be more easily removed from engagementwith the object to be sealed or capped.

In accordance with the present invention, there is thus provided aprotective vinyl end cap for use in sealing the end of a tube or pipe orother article of manufacture in need of a protective end cap. The endcap has a grip surface which includes a textured grip surface generallydifferent from the surface of the remaining portion of the end cap. Thegrip surface in association with the textured surface assists inenhancing the ease of installation and/or removal of the end cap fromengagement with the article to be capped.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an end cap of the present invention.

FIG. 2 is an oblique view of the end cap of FIG. 1.

FIG. 3 is a side view of another end cap of the present invention.

FIG. 4 is an oblique view of the end cap of FIG. 3.

FIGS. 5 and 6 are side views of another end cap of the presentinvention.

FIG. 7 is an oblique view of the end cap of FIGS. 5 and 6.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The invention will be described in connection with FIGS. 1-7.

The end cap 1 of the present invention is made by dip molding. Dipmolding processes are well known in the art, and have been used fordecades to produce vinyl-based plastic articles.

In a dip molding process, a heated mold form or mandrel is dipped into aplastisol bath whereupon a layer of gelled (fused)_plastisol forms aboutthe mandrel. The coated mandrel is removed from the plastisol dippingtank and the coated layer cured, resulting in a molded articlecorresponding in configuration to the configuration of the mandrelemployed. For instance, when a cylindrical mandrel (or pin) is employed,a tubular article with a closed bottom can be produced. Beveragecontainers, bicycle handles, gloves and tubular hose bend restrictorsare but a few of the products that are presently produced by dip moldingby use of a variety of mandrel configurations.

The mandrel may be comprised of any suitable metal such as aluminum,steel, cast iron, brass, copper, titanium, and other ferrous metalcombinations. The mandrel may also be coated with a non-ferrous metal.The mandrel is attached to suitable supporting means during the moldingprocess which causes the mandrel to be dipped into and subsequentlyremoved from the plastisol bath, and also permits the coated mandrel tobe moved along the molding line to other manufacturing stations.

The mandrel is preheated to a temperature sufficient to cause theplastisol in the bath to gel/fuse and to form a layer on the heatedmandrel upon the mandrel being dipped into the plastisol bath. Themandrel is generally preheated to a temperature ranging from about 350degrees F. +/−50 degrees F. by means such as being passed through anoven, placed into a heated liquid bath, heated by internal heatingelement, etc. The particular heating means is not critical as long asthe temperature of the mandrel is sufficiently high to cause therequired gelling of the plastisol on the outer circumferential surfaceof the mandrel once the mandrel is placed into the plastisol bath.

The composition of the plastisol bath is not critical, as a variety ofplastisol compositions are conventionally employed. The plastisol(polyvinylchloride) bath may include various colorants (to cause theformation of a molded article of a particular color), additives,fillers, and/or blowing agents (to cause formation of a foamed layer).Once placed in the plastisol bath, the mandrel is permitted to contactthe plastisol for a time sufficient to result in formation of a gelledlayer on the metallic surface of the mandrel. The time during which themandrel is caused to remain in contact with the plastisol bath isdetermined by a number of factors, such as the temperature of themandrel and the thickness of the gelled plastisol layer which is desiredto be formed on the metallic surface of the mandrel. Generally, it hasbeen found that the mandrel may remain in contact with the plastisolbath for a period of time ranging from about 4 seconds to severalminutes depending on material gellation properties, tooling geometry,and wall thickness desired.

Once the mandrel contacts the plastisol bath for a period of timesufficient to form a gelled layer of desired thickness, the coatedmandrel is removed from the bath. The resulting thickness of the moldedarticle generally ranges from about 0.03 to 0.20 inch. The mandrel isslowly removed from the plastisol bath to enable excess non-gelledplastisol to fall from the mandrel. The mandrel is then cured tosolidify the gelled layer on the mandrel. Such curing may occur byheating to a temperature off from about 390° F. to about 600° F. for aperiod of time ranging from about 0.50 to 3 minutes. Alternatively, theplastisol layer may be cured by dipping the gelled plastisol layer intoa heated bath of molten salt or oil. Such curing means are conventionaland well known to those skilled in the art. The cured plastisol-coatedmandrel is then cooled by conventional means such as by air or water,and the thus-formed dip molded part 1 removed by either mechanicalmeans, air pressure either internal or external to the mandrel, or byother automated methods. The mandrel then typically has a mold releasedplaced over the molding surface and the form is reused to produceadditional molded parts.

If multiple layers of the plastisol are desired, the dipping and/orcuring steps are repeated. The formation of multiple (double dipped)plastisol layers is also well known to those skilled in the art, as isthe use of a blowing agent to form a foamed plastisol layer. See, forexample, U.S. Pat. Nos. 3,904,720 and 4,800,116 in this regard.

The end cap 1 of the present invention has a generally cylindrical ortubular open end 7 and a closed end 9 having formed therein a grippingsurface 5 suitable for gripping between a thumb and finger. The grippingsurface 5 may merely be provided on the exterior of a cylindricalsurface, or the gripping surface may be provided on a molded portionwhich has a different configuration than the rest of the end cap but maybe more specially configured for gripping (such as a thinner orflattened portion as shown in FIGS. 3-7).

It has thus been found that at least a portion of the exterior surfaceof the end cap should be provided with a thin second layer of texturizedsurface 5 to assist gripping as well as installation and/or removal ofthe end cap. Such a coating may be provided by the use of a plastisolbath formulated to provide the desired texturized coating.

Texturized vinyl material may be formulated from a conventionalpolyvinyl chloride plastisol by substituting up to 50% by weight of thevinyl dispersion resin (typically having a particle size of 1 micron orso) with, for example, polyvinyl chloride suspension resin having aparticle size of from 50 to 200 microns, or equivalent course grainedfillers. Exemplary fillers may be selected from a variety ofconventional metal or inorganic fillers having a size and course surfaceto provide the requisite texturized surface properties.

More specifically, various inorganic fillers may be used such as sand,coarse talc, calcium carbonate, etc. However, in order to suspend thefiller particles in the plastisol, it is desirable to keep the filler toas close to the specific gravity as the plastisol as possible. Thefillers can be added in an amount of up to about 30% by weight of thetotal weight of the plastisol composition. Suspension grades ofpolyvinyl chloride with particle sizes ranging from 50 microns andhigher provide a satisfactory textured surface for the dip moldedarticle. Most dispersion grade polyvinyl chloride resins have a particlesize of from 1 to 5 microns.

When large vinyl particles are employed, the use of the larger particlesize allows the plasticizer(s) to only slightly solvate the largerparticle in the plastisol In the case of course non-resinous fillers,the fillers are randomly fused into the solidifying wall duringgellation. As a result, when the plastisol forms a coating 3 on the dipmolded mandrel, or as a second coating 5 on a previously-formed dipmolded part, the coated surface is not smooth but assumes a texturizedsurface due to the presence of the unsolvated particles dispersedthroughout the plastisol.

The resulting end cap 1 having a texturized surface 5 provides manyadvantages. As protective caps and pull caps are generally notergonomically friendly and often difficult to remove, it is highlydesirable for the cap to have a texturized grip surface that is easilyformed yet greatly improves the tactile properties and gripping abilityof the cap. This reduces hand and finger fatigue, and reduces repetitivemotion disorders which occur when a production worker is required torepetitively remove a protective cap for long periods of time.

1. A vinyl pull cap having a texturized grip surface comprising a tubular vinyl dip-molded tubular member having a closed end and an open end, said tubular member having an outer second texturized dip-molded vinyl surface layer covering at least a portion of said tubular member comprising particles of a size and in an amount sufficient to provide a texturized outer vinyl surface.
 2. The vinyl pull cap of claim 1, wherein said particles have a size ranging from 50 to 200 microns.
 3. The vinyl pull cap of claim 1, wherein said particles comprise vinyl resin particles.
 4. The vinyl pull cap of claim 1, wherein said particles comprise filler particles.
 5. The vinyl pull cap of claim 3, wherein said vinyl resin particles have a size ranging from 50 to 200 microns.
 6. The vinyl pull cap of claim 4, wherein said filler particles have a size ranging from 50 to 200 microns.
 7. The vinyl pull cap of claim 1, wherein said tubular member includes a molded grip surface configured to assist gripping by cooperative finger engagement which surface is at least partially covered by said second texturized vinyl surface.
 8. The vinyl pull cap of claim 7, wherein said molded grip surface comprises a flattened portion adjacent said closed end of said tubular member.
 9. The vinyl pull cap of claim 7, wherein said molded grip surface comprises a portion of said closed end having a reduced diameter in relation to the diameter of the tubular member at said open end.
 10. The vinyl pull cap of claim 1, wherein said tubular member is comprised of polyvinyl chloride.
 11. The vinyl pull cap of claim 1, wherein said texturized surface layer is comprised of polyvinyl chloride. 